Nuts
and Bolts

An Introduction to Conservation and Repairs

Jonathan Taylor

Parapet repairs at St Andrews, Cheddar (St Blaise Ltd)

WHAT
IS 'CONSERVATION'?

It is a common misconception
that listed buildings cannot be altered or demolished. They can be. Listing
simply means that all such proposals must be approved by a statutory authority
before work commences. Indeed, some element of alteration is inevitable
as a result of ordinary conservation and repair work, and in some cases
even the demolition of some part may be required in order to ensure the
survival of the building as a whole. Surprised? Conservation is a very broad
concept.

The term 'conservation' encompasses all actions that are required to ensure
the survival of the building in the long term, including, where necessary,
sympathetic alterations. The term 'preservation', on the other hand, is
much more limited in scope, describing only those actions which prevent
change or protect a building from change, and therefore excludes all alterations,
no matter how essential. The third term frequently used in the same context is 'restoration'. This term describes
action taken to reverse more recent alterations and is thus very much a
process of change, removing later alterations and often putting back features
based on the design of elements removed in the past.

In conservation circles restoration is often frowned on due to the number
of poor restoration schemes carried out in the past, often based on the
most vague concept of what might have been, and removing any later features,
irrespective of their historical interest. Medieval buildings in particular
suffered at the hands of Victorian architects who 'restored' features which
had never existed in order to create a thoroughly Gothic aesthetic. In the
best conservation schemes restoration is limited to the bare minimum, so
that the authenticity of the building or object is not compromised. For
example, where crumbling stonework has to be replaced, the new stonework
might be carved to its original profile where it is clear what this would
have been: where the original design is unclear, however, a new design may
be preferable to conservationists since work which imitates the original
can look fake, casting doubt on the authenticity of original elements and
detracting from their historic value. On the other hand, repairs which stand
out can also detract from the enjoyment of original architecture, so a balance
is required where new work can be distinguished from the old without harming
its character.

THE SEVEN DEADLY SINS

Old buildings do not look after themselves, no matter how well constructed.
Most materials are liable to deteriorate when they remain damp for long
periods: iron fixings rust and can shatter the stone into which they are
built; ancient oak beams can be hewn out by deathwatch beetle; and dry rot
can crop up far from the nearest source of damp. Nevertheless, old buildings
have lasted hundreds of years perfectly well with little more than general
maintenance, and arguably the greatest threat to their future comes from
ill-considered intervention by their owners.

Broken roof tiles contributing to damp in the wall below

1.
Poor maintenance
Perhaps the most common causes of dry rot and other forms of timber decay
in old buildings are blocked gutters and the failure of roof coverings (for
example, slipped and broken slates and clay tiles, damaged and stolen lead
and other sheet metal roof coverings). Look out for the tell-tale signs
of damp patches and green algae growth around hoppers and downpipes which
often indicate nothing more complex than leaves or a dead pigeon blocking
the pipe - easily rectified if caught in time. Regular tile slippage can,
however, indicate more fundamental problems as old nails and wooden tile pegs
used to fix the roof coverings often begin to deteriorate all at once.
If ignored, blocked gutters and gaps in the roof covering can cause adjacent
timbers inside the roof to deteriorate, and creating the ideal conditions
for wet rot, dry rot and beetle larvae, often far from the original moisture
source, with little sign of moisture penetration below.

Broken roof tiles contributing to damp in the wall below

Damaged render

2. Sealing damp in with modern renders, sealants
and concrete floors Most old buildings
have solid walls which
keep out the rain due to their mass. Moisture absorbed into the thick
walls is absorbed and retained, but only temporarily. Rough textured surfaces
of natural stone, brickand
lime renders encourage evaporation, and even in the British climate damp
is unlikely to reach the interior in sufficient quantity to become a problem
if the walls are sound and well maintained. Nevertheless, modern paints,
renders and other coatings are often unwisely
applied to overcome a damp problem withoutproperly identifying
its cause, and the results can be disastrous. Impervious surface coatings
lock moisture in and inevitably crack as the structure expands and contracts
with changes in temperature, allowing more moisture in and trapping it.
Covering the floor or relaying it with a damp-proof floor slab membrane
can also prevent natural evaporation, causing moisture to rise through
walls and columns instead. This is often seen as a tide mark of salt crystallisation
and stone decay, one foot or so above floor level.

3. Cement-rich pointing
Although suitable for use in a modern masonry construction, cement rich
mortars can cause substantial damage when used to repoint traditional
masonry. The cement mortars are much harder and allow less movement than
the original lime mortar remaining in the core of the wall. As pointing
usually replaces only the outermost inch or so of mortar, any movement
in the wall will be resisted by the shallow depth of rigid masonry at
the face, causing stress. As a result of this and other factors, such
as salt crystallisation and frost action, pointing with a cement-rich
mortar can often cause masonry to decay.

4. Inappropriate cleaning
Dirt often adheres tightly to surfaces and may extend deep into the pores
of a material. Many of the most effective chemical cleaning methods used
today and all mechanical methods (such as sand blasting, sanding and other
abrasive techniques) are effective because they can remove not only layers
of dirt but also the surface of the material being cleaned, including
metal, glass and stone. The effect of inappropriate cleaning methods can
be seen most clearly in the softening of edges and the loss of more and
more detail with each cleaning. Even the most gentle techniques such as
low pressure water cleaning entail some risk of harm, and proprietary
cleaning products used in the home (for example for cleaning brass) are
no exception. There are almost as many other risks attached to cleaning
as there are cowboy contractors willing to carry it out.

5. Rapid heating systems
Heating systems which are able to introduce rapid or immediate heating
can seem tempting, however, sudden changes in air temperature can cause
serious problems for old buildings. The combination of warm air and still
cold surfaces causes air-borne moisture to condense on walls and windows
in particular, and the sudden rise in temperature causes rapid expansion
and contraction of the fabric of the building and its furnishings. Condensation
on the walls can also make the building feel more cold and damp, reducing
the effect of the heating system as well as contributing to any existing
problems with damp.

Masonry repairs by St Blaise at Lyme Regis church (St Blaise Ltd)

6.The
appointment of non-specialists Because the buildings materials and construction techniques used in the
past are so different from those used today, their conservation and repair
needs to be left to those who have trained in this field and who specialise
in this type of work. Being registered with a professional body such as
the Royal Institution of British Architects (RIBA) or the Royal Institution
of Chartered Surveyors (RICS) does not mean that a professional consultant
is qualified or experienced in conservation work, and building inspections
are regularly carried out by professionals who have little real understanding
of how historic buildings should be repaired. The appointment of building
contractors in particular is a minefield as some highly experienced conservators
have no formal qualification, while many others who claim to specialise
in the field are both unqualified and unskilled. This is why so many buildings
are damaged by poor masonry cleaning, use of the wrong type of mortar and
other inappropriate routine repair work. However, the situation is gradually
improving following the introduction of several accreditation bodies, listed
below, and The Building Conservation Directory provides an excellent
starting point for selecting appropriate specialists.

7. Unsympathetic alterations and repairsIt is obvious that alterations to update or accommodate new facilities will
have a considerable impact on the character of an old building. The impact
of smaller alterations and repairs, however, is more easily overlooked and
often receives little attention at the design stage. For example, the introduction
of new lighting in the interior may require electrical wires to be run in
places where they have not been run before. If not properly planned, by
the time valuable wall paintings or historic wallpapers are discovered under
the plasterwork, a four-inch channel has been chased across them. Similarly,
chasing conduit through roof timbers may result in structural damage, particularly
if the timbers are already overloaded. The results can be catastrophic.
In each case, no matter how small, consider:

the need for the alteration

its effect on the character and enjoyment of the building or component

the archaeological and historical impact of the alteration

its effect on structural performance and durability of the building
or component.

Where the alteration of historically important fittings and fabric is unavoidable,
the original or existing structure should be carefully recorded, before,
during and after alteration, to provide a record not only of the building's
history, but also of the alteration itself so that they can be quickly identified
if any further modifications or repairs are required in the future.

In England and Wales planning is governed by the Town & Country Planning
Act 1990 and the Planning (Listed Buildings and Conservation Areas)
Act 1990, while in Scotland it is governed by the Town & Country
Planning (Scotland) Act 1997and the Planning (Listed Buildings
and Conservation Areas) (Scotland) Act 1997. Further guidance is given
in separate documents for each of the three regions as follows:

Wales:
Welsh Office Circular 61/96, Planning and the Historic Environment:
Historic Buildings and Conservation Areas; and the Welsh Office
Circular 1/98, Planning and the Historic Environment: Directions
by the Secretary of State for Wales.

Despite
this disparity in guidance, the legislation governing the conservation
of the built environment is in many respects identical throughout the
UK. Unlike other
buildings, some ecclesiastical buildings which are in use are exempt from
many aspects of listed building and conservation area legislation, but
not planning permission.

This article is reproduced fromHistoric Churches, 2000

Update, September 2012
Recently there have been several significant changes in UK government planning guidance and policy.

In England Planning Policy Guidance Note 15: Conservation of the Historic Environment (PPG15, 1994) and Planning Policy Guidance Note 16: Archaeology and Planning (PPG16, 1990) have been cancelled by the Government. Initially replaced by Planning Policy Statement 5 (PPS5) in March 2010, current policy guidance for England is now given in the National Planning Policy Framework (NPPF) issued in March 2012. Further guidance is proposed, but in the meantime the guide which originally accompanied PPS5 remains in force - see PPS5 Historic Environment Planning Practice Guide.

In Scotland the principal statutory guidance on policy is now Scottish historic environment policy (SHEP), which was published in December 2011, with subsidiary guidance given in Historic Scotland’s Managing Change leaflets. These documents together replace the Memorandum of Guidance on Listed Buildings and Conservation Areas published in 1998.

Author

JONATHAN TAYLOR is the editor of The Building Conservation Directory and a co-founder of Cathedral Communications Limited. He studied architectural conservation at Heriot-Watt University, Edinburgh and has a background in architectural design, conservation and urban regeneration.